US patent application No 2009/0167704 discloses a device for providing haptic feedback to a user of a touch screen. The device comprises a stack with a first layer of transparent electrode lines, a layer of transparent Piezo-electric material, a second layer of transparent electrode lines that extend perpendicularly to those of the first layer, and a touch screen input layer. The Piezo-electric material shrinks and expands in the direction perpendicular to the layers under influence of electric fields applied between the electrodes on opposite sides of the Piezo-electric layer. The device can give feedback to a user by means of a two dimensional array of selectable surface heights, realized by applying a corresponding pattern of voltage differences between the electrode lines. Obviously, the electrodes do not form a skin layer that can be touched by the user during operation. Large voltage differences need to be maintained between the electrode lines of the first layer electrode lines.
The WO 2010/00261 A1 discloses a transducer for converting between mechanical and electrical energies which comprises a planar electroactive polymer (EAP) layer disposed between two electrodes. In order to induce an anisotropic behavior of the EAP, the electrode layers are corrugated with the help of an intermediate plastically deformable material. WO 2007/099094 similarly discloses a transducer for converting between mechanical and electrical energies. A Piezo-electric layer sandwiched between electrodes is used, the electrodes being made of polymer material. As the outermost layers are conductive electrodes, such a transducer device cannot be used on a surface which is directly touched by users.